From 9027a0b429ad3f2f3f0eb77210f22c4a1d21ee4a Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Wed, 19 Jan 2022 22:07:41 +0300
Subject: Support malloc redirection on E2K (single-threaded mode only)

Issue #413 (bdwgc).

* include/private/gc_priv.h [E2K_USE_SCRATCH] (GC_e2k_ps_buffer,
GC_e2k_ps_capacity): Define macro.
* include/private/gcconfig.h [E2K && LINUX && REDIRECT_MALLOC
&& !GC_LINUX_THREADS] (E2K_USE_SCRATCH): Likewise.
* include/private/gc_priv.h [E2K_USE_SCRATCH] (_GC_arrays): Add
_e2k_ps_buffer and _e2k_ps_capacity fields; add comment.
* include/private/gcconfig.h [E2K && LINUX && REDIRECT_MALLOC
&& GC_LINUX_THREADS && !CPPCHECK]: Issue an error directive.
* mach_dep.c [E2K && E2K_USE_SCRATCH] (GC_free_procedure_stack): Do not
call free(); assert that buf is non-null but GC_e2k_ps_buffer is null;
set GC_e2k_ps_buffer to buf.
* mach_dep.c [E2K && E2K_USE_SCRATCH] (GC_get_procedure_stack):
Initialize buf local variable to GC_e2k_ps_buffer; initialize buf_sz
local variable to GC_e2k_ps_capacity; clear GC_e2k_ps_buffer value;
change FIXME item to TODO one; pass buf to GC_scratch_recycle_no_gww()
instead of free(); call GC_scratch_alloc() instead of malloc().
* mach_dep.c [E2K && LOG_E2K_ALLOCS] (GC_get_procedure_stack): Call
GC_log_printf() to print buf_sz, new_sz and GC_gc_no values if errno
is ENOMEM.
* mach_dep.c [E2K] (GC_get_procedure_stack): Ensure buf_sz<new_sz
(instead of buf_sz!=new_sz) after the loop; return new_sz instead of
buf_sz.
---
 mach_dep.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

(limited to 'mach_dep.c')

diff --git a/mach_dep.c b/mach_dep.c
index c90f8e02..c596bcb7 100644
--- a/mach_dep.c
+++ b/mach_dep.c
@@ -67,15 +67,29 @@
         } while (0)
 
   GC_INNER void GC_free_procedure_stack(ptr_t buf) {
-    free(buf);
+#   ifdef E2K_USE_SCRATCH
+      GC_ASSERT(buf != NULL);
+      GC_ASSERT(NULL == GC_e2k_ps_buffer);
+      GC_e2k_ps_buffer = buf; /* the buffer could be reused */
+#   else
+      free(buf);
+#   endif
   }
 
   GC_INNER size_t GC_get_procedure_stack(ptr_t *buf_ptr) {
     word ps;
-    ptr_t buf = NULL;
-    word buf_sz = 0;
+    ptr_t buf;
+    word buf_sz;
     word new_sz = 0;
 
+#   ifdef E2K_USE_SCRATCH
+      buf = GC_e2k_ps_buffer;
+      buf_sz = (word)GC_e2k_ps_capacity;
+      GC_e2k_ps_buffer = NULL; /* indicate the buffer is in use */
+#   else
+      buf = NULL;
+      buf_sz = 0;
+#   endif
     get_stack_index(&ps);
     for (;;) {
       int res = syscall(__NR_access_hw_stacks, E2K_READ_PROCEDURE_STACK,
@@ -83,9 +97,22 @@
 
       if (res != -1) break;
       if (ENOMEM == errno && buf_sz != new_sz) {
-        /* FIXME: use GC_scratch_alloc to support malloc redirection? */
-        free(buf);
-        buf = malloc((size_t)new_sz);
+#       ifdef LOG_E2K_ALLOCS
+          GC_log_printf("GC_get_procedure_stack(): free/alloc %lu/%lu bytes,"
+                        " GC #%lu\n",
+                        (unsigned long)buf_sz, (unsigned long)new_sz,
+                        (unsigned long)GC_gc_no);
+#       endif
+#       ifdef E2K_USE_SCRATCH
+          GC_ASSERT(new_sz > (word)GC_e2k_ps_capacity);
+          GC_scratch_recycle_no_gww(buf, GC_e2k_ps_capacity);
+          buf = GC_scratch_alloc((size_t)new_sz);
+          GC_e2k_ps_capacity = (size_t)new_sz;
+          /* TODO: support malloc redirection if multi-threaded */
+#       else
+          free(buf);
+          buf = malloc((size_t)new_sz);
+#       endif
         if (NULL == buf)
           ABORT_ARG1("Could not allocate memory for procedure stack",
                      ", %lu bytes requested", (unsigned long)new_sz);
@@ -100,13 +127,13 @@
       get_stack_index(&ps);
     }
 
-    if (buf_sz != new_sz)
+    if (buf_sz < new_sz)
       ABORT_ARG2("Buffer size mismatch while reading procedure stack",
                  ": buf_sz= %lu, new_sz= %lu",
                  (unsigned long)buf_sz, (unsigned long)new_sz);
     GC_ASSERT(buf != NULL);
     *buf_ptr = buf;
-    return (size_t)buf_sz;
+    return (size_t)new_sz;
   }
 
   ptr_t GC_save_regs_in_stack(void) {
-- 
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